RASOANAIVO chemosensitizers in malaria therapy

Bloomfontein, 24-27th October 2004

Strychnos myrtoides and
chemosensitizers in malaria therapy:
From traditional to clinical trials and
drug development

Philippe Rasoanaivo
Institut Malgache de Recherches Appliquées
Antananarivo, Madagascar

World incidence of malaria

DRUG RESISTANCE

Life cycle

LIVING ORGANISMS

How to overcome drug resistance ?

Optimizing
existing drugs
Leads
Chemosensitizers

1980-1985 :sudden malaria recrudescence
in the Highlands of Madagascar

Strychnos myrtoides

Preliminary investigation of Strychnos myrtoides
1.00

50

In vitro

0.80

In vivo

45
40
35

0.60

30
25
20

0.40

15
10

0.20

5
0
0.00

1
0.00

0.20

0.40

N

0.60

0.80

2

Ac

4

CH3

O

H

N

3

1.00

N
CO2CH3

H
O

Malagashanine

CH3

N
O

CH3 O

CH3

Strychnobrasiline

Rasoanaivo P, Ratsimamanga S, Milijaona R, et al. Planta Medica 1994, 60, 13.

Strychnos diplotricha

Strychnos myrtoides

Strychnos mostueoides

M.-T. Martin P. Rasoanaivo, G. Palazzino, et al. Phytochemistry 1999, 51, 479.
P. Rasoanaivo, G. Palazzino, C. Galeffi and M. Nicoletti. Phytochemistry 2001, 56/8, 863.

Traditional recipe

Clinical trials

Clinical observational study

A. Ramialiarisoa, J. Ranaivoravo, P. Rasoanaivo et al., Révue de Médecine et
Pharmacopée Africaines 1994, 8, 123.

Pre-clinical investigations
Phytochemistry
Pharmacology
Toxicology
Pharmacokinetics

Controlled, double blind randomized clinical trial

One relevant pharmacological result
1.00

Fractional IC50 Malagashanine

0.80

0.60

0.40

0.20

0.00
0.00

0.20

0.40

0.60

0.80

1.00

Fractional IC50 Chloroquine

H. Rafatro, D. Ramanitrahasimbola, P. Rasoanaivo, et al.
Biochemical Pharmacology 2000, 59(9), 1053.

Ankazobe ~ 100 km from Antananarivo

Chloroquine + standardized phytomedicine
versus
Chloroquine

Results of the clinical trial
Adequate clinical response
at D14
Positif

Negative

Parasite clearance
at D14
Positif

Negative

Chloroquine
+
placebo

142

19

124

33

Chloroquine
+
phytomedicine

138

18

125

29

TOTAL

280

37

249

62

13,2%

24.9%
Therapeutic failure

Results of the in vitro susceptibility test
ƒ 404 blood samples collected
ƒ 291 positive culture
ƒ 244 interpretable results
‰ 190 sensible isolates
‰ 58 middle resistant isolates
‰ 4 resistant isolates

Evolution of parasite suceptibility
in the same patient
1.00

IC = 3.18 µg/ml,

At inclusion IC50 = 12.35 µg/ml
90

0.80

After one week
continuous culture

After one month

0.60

IC50 = 2.51 µg/ml
IC90 = 17.28 µg/ml

0.40

IC50 = 2.38 µg/ml
IC90 = 17.97 µg/ml

0.20

0.00
0.00

0.20

0.40

0.60

0.80

1.00

Traditional recipe

Bioactive compounds

Source of inspiration

Drug discovery

Chemosensitizing
Pharmacophore

Malagashanine
Synthetic chemosensitizers
MeO
N
MeO

CN

MeO

N

N
H

Desipramine

N

OMe

Verapamil

Cyproteptadine
CH3

N
H

Naturally-occurring
chemosensitizer

CO2CH3

N
H
Ac

O

Malagashanine

N-phenyl-1,3-diamino-propane unit
CH3
N

CO2CH3

N
Ac

N
O

Malagashanine

Desipramine

N
N
H

N
H

1-phenyl-4-amino unit
NC

CH3

H3CO

N

H3CO

Verapamil

OCH3

OCH3

CH3
N

N
Cyproteptadine

Synthesis of derivatives

X

N

R
X = N, C
Bioorg Med Chem Letters (in preparation)

1,4-diamino unit
N

CH3

CO2CH3

N
H
O

Unifying chemosensitizing pharmacophore
R = Alkyl, Phenyl
S’ = N, Phenyl

R

S

(C)n

S'

S = C, N, Phenyl
P Rasoanaivo, D Ramanitrahasimbola, O. Rakotonandrasana, Ethnopharmacologia 2004 (in press)

One confirmation: the pervilleine series
H3CO

OCH3
OCH3
CH33
N

O
O
OCH3
OCH3

O
O

OCH3

B. Cui, G. L. Silva, D. Chavez, M. You, H.-B. Chai, P. Rasoanaivo, S. M. Lynn, M. O’Neill,
J. A. Lewis, J. M. Besterman, A. Monks, N. R. Farnsworth, G. A. Cordell, J. M. Pezzuto,
A. D. Kinghorn. Journal of Natural Products 2001, 64(12), 1514.

Chemosensitizing pharmacophore and polyamines
NH2

H2N

Putrescine
H2N

N
H

NH2

Spermidine
CH3

NC
H3CO

N

OCH3

Verapamil

H3CO

OCH3

CH3
OCH3

OCH3

N

OCH3

H3CO
O

H3CO

O

O

H2N

O

H
N
N
H

Spermine

OCH3

NH2

Interestingly,
chloroquine has a 1,4-diamino unit
HN

Cl

N

N

Chloroquine
Malagashanine

useful biochemical tool

Hypothesis of a reversible CQ transporter

D. Ramanitrahasimbola, P. Rasoanaivo, H. Vial, Biochem Pharmacol (submitted)

Hemisynthesis
O

N
N

CH3

CH3

8 steps

N
O

CO2CH3

N
CH3

O

CH3

O

N

CH3
N

CH3

CO2CH3

N

CO2CH3

N
O

O

F Trigalo, R Joyeau, VC Pham, JJ Youté, P Rasoanaivo, F Frappier .
Tetrahedron 2004, 65, 5471-74.

In summary:
Ethnomedical knowledge
Bioactive compounds
Leads

Drug development

Phytomedicines

Biochemical tool
Synthesis
New activities

Drug
mechanism

Acknowledgements
Muséum National d’Histoire Naturelle
Università degli Studi di Roma “La Sapienza”
Institut de Chimie des Substances Naturelles
Université de Montpellier 2
University of Cape Town

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P
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Natural Products and Drug Discovery

August 9-12, 2005
Antananarivo, Madagascar